1. Field of the Invention
The present invention relates to an aromatic block polycarbonate resin which is useful as the photoconductive material for use in the electrophotographic photoconductor, and the production process of the aromatic block polycarbonate resin. The present invention also relates to a diphenol compound used to produce the above-mentioned polycarbonate resin, and the production process of the diphenol compound. Further, the present invention relates to an electrophotographic photoconductor comprising an electroconductive support and a photoconductive layer formed thereon, comprising the above-mentioned aromatic block polycarbonate resin. In addition, the present invention also relates to an electrophotographic image forming apparatus and method using the above-mentioned photoconductor, and a process cartridge which is freely attachable to the image forming apparatus and detachable therefrom.
2. Discussion of Background
Conventionally known representative aromatic polycarbonate resins are obtained by allowing 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A) to react with phosgene or diphenylcarbonate. Such polycarbonate resins made from bisphenol A are used in many fields because of their excellent characteristics, such as high transparency, high heat resistance, high dimensional accuracy, and high mechanical strength.
For example, this kind of polycarbonate resin is intensively studied as a binder resin for use in an organic photoconductor in the electrophotographic field.
Recently organic photoconductors (OPC) are used in many copying machines and printers. These organic photoconductors have a layered structure comprising a charge generation layer (CGL) and a charge transport layer (CTL) which are successively overlaid on an electroconductive support. The charge transport layer (CTL) comprises a binder resin and a low-molecular-weight charge transport material (CTM). The addition of such a low-molecular-weight charge transport material (CTM) to the binder resin lowers the intrinsic mechanical strength of the binder resin, so that the CTL film becomes fragile. The result is that the abrasion resistance of the photoconductor is lowered, so that scratches and cracks are easily formed on the surface of the photoconductor. The durability of the photoconductor is thus impaired.
Although some vinyl polymers such as polyvinyl anthracene, polyvinyl pyrene and poly-N-vinylcarbazole have been studied as high-molecular weight photoconductive materials for forming a charge transport complex for use in the conventional organic photoconductor, such polymers are not satisfactory from the viewpoint of photosensitivity.
In addition, high-molecular weight materials having charge transporting properties have been also studied to eliminate the shortcomings of the above-mentioned layered photoconductor. For instance, there are proposed an acrylic resin having a triphenylamine structure as reported by M. Stolka et al., in xe2x80x9cJ. Polym. Sci., vol 21, 969 (1963)xe2x80x9d; a vinyl polymer having a hydrazone structure as described in xe2x80x9cJapan Hard Copy ""89 p. 67xe2x80x9d; and polycarbonate resins having a triarylamine structure as disclosed in U.S. Pat. Nos. 4,801,517, 4,806,443, 4,806,444, 4,937,165, 4,959,288, 5,030,532, 5,034,296, and 5,080,989, and Japanese Laid-Open Patent Applications Nos. 64-9964, 3-221522, 2-304456, 4-11627, 4-175337, 4-18371, 4-31404, and 4-133065. However, any materials have not yet been put to practical use.
According to the report of xe2x80x9cPhysical Review B46 6705 (1992)xe2x80x9d by M. A. Abkowitz et al., it is confirmed that the drift mobility of a high-molecular weight charge transport material is lower than that of a low-molecular weight material by one figure. This report is based on the comparison between the photoconductor comprising a low-molecular weight tetraarylbenzidine derivative dispersed in the photoconductive layer and the one comprising a high-molecular polycarbonate having a tetraarylbenzidine structure in its molecule. The reason for this has not been clarified, but it is considered that the photoconductor employing the high-molecular weight charge transport material produces poor results in terms of the photosensitivity and the residual potential although the mechanical strength of the photoconductor is improved.
To solve the above-mentioned problem, various copolymers having a triarylamine structure were put forward as the high-molecular weight photoconductive materials. Most of these copolymers are in the form of a random copolymer or an alternating copolymer. Although each copolymer includes a charge transporting monomer and a monomer capable of improving the wear resistance, such charge transporting properties and wear resistance improving properties are leveled when those monomers are combined in the form of a random or alternating copolymer. The conventional photoconductors employing the above-mentioned random or alternating copolymers cannot meet the overall requirements.
It is therefore a first object of the present invention to provide an aromatic polycarbonate resin useful as the high-molecular weight material with charge transporting properties for use in the organic electrophotographic photoconductor.
A second object of the present invention is to provide a production process of the above-mentioned aromatic polycarbonate resin.
A third object of the present invention is to provide a diphenol compound serving to produce the above-mentioned aromatic polycarbonate resin.
A fourth object of the present invention is to provide a production process of the diphenol compound.
A fifth object of the present invention is to provide an electrophotographic photoconductor with high sensitivity and durability.
A sixth object of the present invention is to provide an electrophotographic process.
A seventh object of the present invention is to provide an electrophotographic image forming apparatus.
An eighth object of the present invention is to provide a process cartridge freely detachable from the image forming apparatus.
The above-mentioned first object of the present invention can be achieved by an aromatic block polycarbonate resin prepared by polymerizing a diphenol compound having a tertiary amine structure, a diol compound represented by formula (1), and a halogenated carbonyl compound, 
wherein n is an integer of 1 to 50, and X is a substituted or unsubstituted bivalent aliphatic group, a substituted or unsubstituted bivalent cyclic aliphatic group, a substituted or unsubstituted bivalent aromatic group, a bivalent group prepared by bonding the aforementioned bivalent groups, or a bivalent group represented by formula (1-a), (1-b), or (1-c): 
in which R1, R2, R3, and R4 are each independently an alkyl group which may have a substituent, an aryl group which may have a substituent, or a halogen atom; a and b are each independently an integer of 0 to 4; c and d are each independently an integer of 0 to 3; and l is an integer of 0 or 1, and when l=1, Y is a straight-chain alkylene group having 2 to 12 carbon atoms, a substituted or unsubstituted branched alkylene group having 3 to 12 carbon atoms, a bivalent group comprising at least one alkylene group having 1 to 10 carbon atoms, and at least one oxygen atom and/or one sulfur atom, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, 
in which Z1 and Z2 are each a substituted or unsubstituted bivalent aliphatic group, or a substituted or unsubstituted arylene group; R5, R6, and R12 are each independently a halogen atom, a substituted or unsubstituted alkyl group, a substituted or un substituted alkoxyl group, or a substituted or unsubstituted aryl group; R7, R8, R9, R10, and R11 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxyl group, or a substituted or unsubstituted aryl group, and R6 and R7 may form together a carbon ring having 5 to 12 carbon atoms; lxe2x80x2 and lxe2x80x3 are each an integer of 0 or 1, and when lxe2x80x2=1 and lxe2x80x3=1, R13 and R14 are each an alkylene group having 1 to 4 carbon atoms, R15 and R16 are each independently a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; e and g are each independently an integer of 0 to 4; f is an integer of 1 or 2; h is an integer of 0 to 20; and i is an integer of 0 to 2000.
In the above-mentioned aromatic block polycarbonate resin, it is preferable that the diphenol compound be represented by formula (2): 
wherein Ar1, Ar2, and Ar3 are each a substituted or unsubstituted arylene group; and R17 and R18, which may be the same or different, are each an acyl group, an alkyl group which may have a substituent, or an aryl group which may have a substituent.
The first object of the present invention can be achieved by an aromatic block polycarbonate resin of formula (3): 
wherein Ar1, Ar2, Ar3, R17, R18, X, and n are the same as those previously defined; and k and j represent the composition ratios, and 0 less than k/(k+j) less than 1.
The first object of the present invention can also be achieved by an aromatic block polycarbonate resin of formula (6) prepared by polymerizing a diphenol compound represented by formula (4), a diol compound represented by formula (5), and a halogenated carbonyl compound, 
wherein Ar1, Ar2, Ar3, R17, R18, X, m, k, and j are the same as those previously defined.
The first object can also be achieved by an aromatic block polycarbonate resin represented by the following formula (7), prepared by polymerizing the diphenol compound of formula (4), the diol compound of formula (1), and the halogenated carbonyl compound: 
wherein Ar1, Ar2, Ar3, R17, R18, and X are the same as those previously defined; n is an integer of 1 to 50; m is an integer of 1 to 30; and k and j represent the composition ratios, and 0 less than k/(k+j) less than 1.
It is preferable that the diol compound of formula (1) used to produce the aromatic block polycarbonate resin have a number-average molecular weight of 500 to 100,000.
Further, it is preferable that the diphenol compound of formula (4) used to produce the aromatic block polycarbonate resin have a number-average molecular weight of 500 to 100,000.
The second object of the present invention can be achieved by a method of producing an aromatic block polycarbonate resin, comprising the steps of polymerizing a diol compound of formula (5) and a halogenated carbonyl compound by solution polymerization or interfacial polymerization, thereby preparing a diol compound of formula (1); polymerizing a diphenol compound of formula (2) and a halogenated carbonyl compound by solution polymerization or interfacial polymerization, thereby preparing a diphenol compound of formula (4); and polymerizing the diol compound of formula (1), the diphenol compound of formula (4), and a halogenated carbonyl compound, thereby preparing the aromatic block polycarbonate resin of formula (7).
The second object of the present invention can also be achieved by a method of producing an aromatic block polycarbonate resin, comprising the steps of polymerizing a dial compound of formula (5) and a halogenated carbonyl compound by solution polymerization or interfacial polymerization, thereby preparing a diol compound of formula (1); and polymerizing the dial compound of formula (1), a diphenol compound of formula (2), a halogenated carbonyl compound, with the addition thereto of a catalyst and a solvent, thereby preparing an aromatic block polycarbonate resin of formula (3).
Further, the second object can be achieved by a method of producing an aromatic block polycarbonate resin, comprising the steps of polymerizing a diphenol compound of formula (2) and a halogenated carbonyl compound by solution polymerization or interfacial polymerization, thereby preparing a diphenol compound of formula (4); and polymerizing the diphenol compound of formula (4), a diol compound of formula (5), a halogenated carbonyl compound, with the addition thereto of a catalyst and a solvent, thereby preparing an aromatic block polycarbonate resin of formula (6).
The third object of the present invention can be achieved by a diphenol compound of formula (4) comprising a tertiary amine structure: 
wherein Ar1, Ar2, and Ar3 are each a substituted or unsubstituted arylene group; R17 and R18, which may be the same or different, are each an acyl group, an alkyl group which may have a substituent, or an aryl group which may have a substituent; and m is an integer of 1 to 30.
The above-mentioned fourth object of the present invention can be achieved by a method of producing the diphenol compound of formula (4) comprising the step of polymerizing a diphenol compound of formula (2) and a halogenated carbonyl compound by solution polymerization or interfacial polymerization: 
wherein Ar1, Ar2, Ar3, R17, and R18 are the same as those previously defined.
The fifth object of the present invention can be achieved by an electrophotographic photoconductor comprising an electroconductive support, and a photoconductive layer formed thereon comprising as an effective component at least one of the above-mentioned aromatic block polycarbonate resins, such as the above-mentioned aromatic block polycarbonate resin of formula (3), (6), or (7).
In the electrophotographic photoconductor, the photoconductive layer may further comprise a charge generation material.
Further, the photoconductive layer may comprise a charge generation layer and a charge transport layer which are successively provided on the electroconductive support, the charge transport layer comprising the aromatic block polycarbonate resin.
In this case, the charge generation layer may be provided on the charge transport layer, or the charge transport layer may be provided on the charge generation layer.
When the charge generation layer is provided on the charge transport layer, a protective layer which comprises the aromatic block polycarbonate resin may be provided on the charge generation layer.
When the charge transport layer is provided on the charge generation layer, the charge transport layer may comprise a first charge transport layer and a second charge transport layer which are successively overlaid on the charge generation layer in this order, the second charge transport layer comprising the aromatic block polycarbonate resin.
When the electrophotographic photoconductor comprises a single-layered photoconductive layer, a protective layer which comprises the aromatic block polycarbonate resin is provided on the photoconductive layer.
The sixth object of the present invention can be achieved by an electrophotographic image forming method comprising the steps of charging the surface of an electrophotographic photoconductor, exposing the charged surface of the photoconductor to a light image, thereby forming a latent electrostatic image on the photoconductor, developing the latent electrostatic image to a visible image, transferring the visible image to an image receiving member, cleaning the surface of the photoconductor, and quenching the residual potential on the surface of the photoconductor, wherein any of the above-mentioned electrophotographic photoconductors employing the aromatic block polycarbonate resin is employed.
The seventh object of the present invention can be achieved by an electrophotographic image forming apparatus comprising an electrophotographic photoconductor capable of forming a latent electrostatic image thereon, charging means for charging the surface of the photoconductor, light exposure means for exposing the charged surface of the photoconductor to a light image, thereby forming a latent electrostatic image on the photoconductor, developing means for developing the latent electrostatic image to a visible image, and image transfer means for transferring the visible image to an image receiving member, wherein any of the above-mentioned electrophotographic photoconductors employing the aromatic block polycarbonate resin is employed.
The eighth object of the present invention can be achieved by a process cartridge which is freely attachable to an electrophotographic image forming apparatus and detachable therefrom, the process cartridge comprising an electrophotographic photoconductor, and at least one means selected from the group consisting of a charging means for charging the surface of the photoconductor, a light exposure means for exposing the photoconductor to a light image to form a latent electrostatic image on the photoconductor, a developing means for developing the latent electrostatic image to a visible image, an image transfer means for transferring the visible image formed on the photoconductor to an image receiving member s and a cleaning means for cleaning the surface of the photoconductor, wherein any of the above-mentioned electrophotographic photoconductors employing the aromatic block polycarbonate resin is employed.